Would it be better to run an SPI connection through the LTC or Bit bang it?

Discussion of developmental aspects of the MiSTer Project.
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Joined: Fri Oct 02, 2020 10:35 pm

Would it be better to run an SPI connection through the LTC or Bit bang it?

Unread post by bugwhacker »

I know it seems obvious to just program the SPI port to be used as an SPI port but I don't know which system can afford the bandwidth to run a Vector monitor over SPI.

If it matters I have the digital I/O board and I am using an Hdmi DAC running on arcade monitors for video right now. I am pretty sure the SPI protocol could be bit banged out over the same GPIO as the the original VGA board.

I have seen a video of someone who had it working to an extent so I am encouraged by that.

Ultimately I am wanting to run Vector monitors for all the Vector games but it looked like they Bit-banged it out over GPIO.

I realize I may be one of the few that would ever want to do such a thing but honestly the Arcade cores are maturing in such a nice fashion that I am ready to stop fixing arcade boards but not ready to stop playing on real cabinets with CRT's.

Any help on which way would be a better direction to start out would be helpful (Sorgelig?) Or if someone knew how to get ahold of ElectronAsh @ Twitter in some other way that would be helpful (I don't do Twitter...)

As another thought it could be sent over SPIDF/Coaxial audio much like https://www.youtube.com/watch?v=SRmgAqyIweU Oscilloscope Music. There is more than enough bandwidth and honestly a Vector monitor is basically fed from an audio amp anyway....

Analog has a 16 channel SPI DAC project board that plugs into the LTC port of the DE-10.

https://www.analog.com/en/design-center ... 25a-a.html16 channels @ 12bit or 16bit depth.

Its $100 and could conceivably give you 16 channel control to 4 or more devices.

Monitor 1 = X/Y/Z for Color Vector Monitors. 3 channels
Monitor 1 = X/Y for B/W Vector Monitors. 2 channels
Monitor 2 = RGBs for Combined Sync Monitors. 4 channels
Monitor 3 = RGBHV for Separate Sync Monitors. 5 channels

1 possible use I can see is driving a static picture to an LCD Marquee display while using another channel to actually display the Game, or maybe you love 2 display Arcade games (punch out?).
Just some thoughts.
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